The 500-M-Long Spaceship Kangaroo Is at Rest on the Planet

Multiple Choice

The 500-m-long spaceship Kangaroo is at rest on the planet Hitest for refuelling. Another spaceship, Echidna, passes parallel to Kangaroo at 0.600c. The crew on Kangaroo measure the length of Echidna as it passes and find that the length they measure is exactly the same as the known 500 m rest length of Kangaroo. If Echidna were at rest next to Kangaroo, its length would then be measured to be:

A) 180 m.
B) 320 m.
C) 500 m.
D) 625 m.
E) 781 m.